i would like to know if we choose a efflux pump inhibitor; should it necessarily have antimicrobial property?

suppose its non-antimicrobial..will it reduce biofilm formation??

Your aims are noz defined properly. There are several efflux inhibitors:   as Calcium antagonists, phenothiazines, proton pump inhibitors for bacteria and cancer or normal cells. fFr cancer cells the phenothiazines and proton pump inhivbitors, HSP90 analogues. For normal  tissues, Pgp in the  brain capillary endothelial cells  tomato lectin  can be recommended in tissue cultures. 

Hi, I would say that if the efflux pump inihibitor(s) is able to cause severe harm to the microbe cell and then lead to death, then it would be bactericidal (leading less cells in biofilm and gradual weakening of biofilm) but if not, then you would have to investigate how else is it capable of reducing biofilm? - through prevention of adhesion (perhaps through adhesion property alterations or quorum sensing inhibition)  or disruption of the biofilm structure (perhaps through matrix based actions) or when combined with antibiotics, reduces the efflux of the drugs and thus increase the microbe's sensitivity. 

If the efflux pump inhibitor is able to prevent the extrusion of biofilm specific factor like quorum sensing molecule then it might interfere with biofilm formation. If it is working in this manner, it need not be antimicrobial in nature. Infact if the EPI is antimicrobial in nature, it would be tough to dissect out EPI effect from antibacterial effect. But a work from Prof Piddock's group (https://www.ncbi.nlm.nih.gov/pubmed/24176982)  showed that EPI caused biofilm inhibition by transcriptional repression of biofilm matrix components and not actually by its efflux inhibitory effect.

Hi,

Talking about efflux pump inhibitors in my last review

https://www.tandfonline.com/doi/abs/10.1080/17460441.2018.1455660?journalCode=iedc20

Regards